Tube bundle assembly

ABSTRACT

A tube bundle assembly, for example, a heat exchanger tube bundle or a nuclear fuel element tube bundle, comprises a bundle of laterally spaced tubes, a frame around the outermost tubes, and a lattice of wire cables with their ends held against lateral displacement by the frame and the tubes in the lattice interstices. The cables are deflected round a portion of each tube to space the tubes from one another, and the cables are preferably tensioned against the frame for this purpose.

Pettigrew 1 Sept. 24, 1974 TUBE BUNDLE ASSEMBLY 3,637,008 1/1972 Michel et al 165/69 [75] Inventor: Michel J. Pettigrew, Deep River,

Ontario, Canada Primary Examiner-Charles Sukalo [73] Assignee: Atomic Energy of Canada Limited, Attorney Agent or Firm-John Hora Ontario, Canada [22] Filed: Feb. 14, 1972 RACT {21] Appl No.: 226,161 A tube bundle assembly, for example, a heat exchanger tube bundle or a nuclear fuel element tube bundle, comprises a bundle of laterally spaced tubes, a [30] Foreign Apphcamn Priority Data frame around the outermost tubes, and a lattice of Mar. 19, 1971 Canada 108225 wire cables with their ends held against lateral placement by the frame and the tubes in the lattice in- [52] US. Cl. 165/162 terstices. [51] Int. Cl. F28d 7/00 The cables are deflected round a portion of each tube [58] Field of Search 165/69, 162, 67 to space the tubes from one another, and the Cables [56] References Cited ar; grszferably tensioned against the frame for this UNITED STATES PATENTS p p 3,292,691 12/1966 Welter et al. 165/ 162 9 Claims, 10 Drawing Figures PATENTEDSEP24|9M 3.831. 397 SHEET 30F 4 FIGJO. 4

my; 7 v

This invention relates to tube bundle assemblies.

In, for example, heat exchanger tube bundle assem blies, it is necessary to space adjacent tubes in triangu-- lar array to permit fluid to flow around the tubes for heat exchange with a fluid within the tubes. The means spacing the tubes in this manner should preferably have the following features:

1. Minimum diametral clearance with the tubes or preferably positive tube holding characteristics to retard or prevent fretting at the interface between the tube and spacing means,

2. Good damping characteristics to absorb any vibration generated by fluid flowing around or along the tubes,

3. Be inexpensive,

4. Be easily assembled with the tubes, and

5. Offer the least possible obstruction to fluid flowing between the tubes.

It is an object of the present invention to provide a tube bundle assembly having means spacing the tubes which causes minimal fretting with the tubes, has good damping characteristics, is inexpensive and easily assembled with the tubes, and which provides small resistance to flow of fluid along the tubes.

According to the present invention there is provided a tube bundle assembly, comprising a bundle of laterally spaced tubes, a frame around the outermost tubes holding them in position, a lattice of wire cables with their ends held against lateral displacement by the frame and at least all but the outermost tubes each in a lattice interstice, and each wire cable deflected round a portion of each tube adjacent thereto to space the tubes in triangular arrays in an endwise direction.

In the accompanying drawings which illustrate by way of example, embodiments of the invention,

FIG. 1 is an end view of a tube bundle assembly FIG. 2 is an end view of a different tube bundle assembly,

FIG. 3 is an end view of yet another tube bundle assembly,

FIG. 4 is a sectional side view of the tube bundle assembly shown in FIG. 2 in a casing,

FIG. 5 is a partly sectioned side view ofa nuclear fuel element tube bundle,

FIG. 6 is an end view of FIG. 5,

FIG. 7 is a sectional end view along VII-VII, FIG. 5,

FIG. 8 is a part view of a different nuclear fuel element tube bundle to that shown in FIGS. 5 to 7,

FIG. 9 is a sectional end view along IX-IX, FIG. 8, and

FIG. 10 is a partly sectioned, side view of a portion of yet another different nuclear fuel element tube bundle assembly to that shown in FIGS. 5 to 7.

Referring to FIG. 1 there is shown a tube bundle assembly, comprising a bundle of laterally spaced tubes 1 and 2, a frame 4 around the outermost tubes 2 holding them in position, a lattice 6 of wire cables 8 and 10 with their ends held against lateral displacement by the frame 4 and all but the outermost tubes 2 (that is all of the tubes 1) each in a lattice interstice 12, and each wire cable deflected round a portion of each tube 1 and 2 adjacent thereto to space the tubes 1 and 2 in triangular arrays in an endwise direction.

The wire cables 1 and 3 are stranded steel wire cables, preferably of circular cross-section each of slightly larger diameter D than the distance T between any of the adjacent tubes 1 and 2. As an example, if the tubes 1 and 2 have an outside diameter of 0.50 inches, and the gap T is 0.150 inches, then cables 1 and 2 having an outside diameter of 0.160 inches are suitable.

The outermost tubes 2 are preferably held in position by being located in curved recesses 16 and in the frame The ends of the cables 8 and 10 in this embodiment are held against lateral displacement by being slid into close fitting bores 14 and 15 respectively, in the frame 4 If desired the cables 1 and 2 may be attached to the frame 4 by being welded in the bores 14. However, it is preferable for the cables 8 and 10 to be removably secured in the holes 14 in the frame 4 by, for example, wedges or screw threaded connections to facilitate replacement of one of the tubes 1 and 2 or of one of the cables 8 and10.

In FIG. 2, similar parts to those shown in FIG. 1 are designated by the same reference numerals, and the previous description is relied upon to describe them.

In FIG. 2 further cables 18 similar to cables 8 and 10 extend along paths between the tubes on either side of the positions 20 at which the lattice wire cables 8 and 10 cross one another, the further wire cables 18 have their ends held against lateral displacement by the frame 4 and are deflected round the tubes 1 and 2 to space them.

The further cables 18 are slid into close fitting bores 22 in the same manner as the cables 8 and 10 are slid into bores 14 and 15 respectively, and may be secured therein if desired.

With this embodiment the tubes 1 and 2 are held more firmly in position by the cables 8, l0 and 18 than by the cables 8 and 10 alone as in the embodiment shown in FIG. 2. Thus where a robust tube bundle assembly is required this embodiment is preferred.

In FIG. 3 similar parts to those shown in FIGS. 1 and 2 are designated by the same reference numerals, and the previous descriptions are relied upon to describe them.

In FIG. 3 the tubes 1 and 2 are within a frame 24 having countersunk holes 26 for tensioning devices 29 for cables 28 to 30. Each cable 28 to 30 has a threaded ferrule 32 welded to one end, and a tensioning nut 34 is screwed on to it. The threads on the ferrules 32 and nuts 34 have a helix which causes the nuts 34 to be rotated in a direction which will tighten the strands of the cables 28 to 30 when tensioning the cables 28 to 30.

The other ends of the cables 28 to 30 have a ferrule- 36 welded to their ends and located in countersunk holes 38.

It will be noted that the cables 28 different paths between the tubes 8 and 10in FIG. 1.

In FIG. 4 the embodiment shown in FIG. 2 is used as an example to assemble a tube bundle within a cylindrical casing 38. It will be appreciated that the embodiments shown in FIGS. 1 and 3 can also be used to assemble a tube bundle in a casing in the same manner.

to 30 extend along 1 and 2 to the cables The tubes 1 and 2 are spaced at each end by cables,

fit with the internal diameter of the casing 38.

In other embodiments of the invention braided, flat cables may be used with the flat sides in contact with the tubes. Braided flat cables have the advantage of providing line contact with the tubes, and increased strength, particularly where the spacings between the tubes is small.

It will be seen that using cables to space tubes according to the invention will 1. Provide positive tube holding characteristics and retard fretting at the interfaces between the tubes and the cables,

2. Provide good damping characteristics to absorb any vibrations generated by fluid flowing around or along the tubes,

3. Provide an inexpensive mounting for the tubes,

4. Provide an easily assembled mounting for the tubes, and

5. Offer little obstruction to fluid flowing between the tubes because the rows of cables are staggered, that is the rows are in different planes, and the fluid flows around one row before flowing round the next row.

It will be appreciated that the outer contour of the frame 4 may be any desired shape to suit the interior of the casing 38 or for compactness may be part of the casing 38.

In other embodiments the casing 38 having an interior of circular cross-section may have two or more sectorshaped frames fltted in to it to fill the interior with tubes, for example two half moon shaped frames may be used. Naturally, in other embodiments where the casing does not have an interior of circular crosssection the interior may be fitted with two or more frames of other shapes to fill the interior with tubes.

Whilst it is preferable for the deflections of the cables to visually indicate a curved deflection round a portion of each tube, the deflection may in some instances be sufficiently small for each cable I to appear to be straight.

Preferably the cables are of stainless steel, but is some instances they may be of another material such as aluminum or nickel alloy, and where working temperatures permit, a plastic material such as a polyamide or polytetrafluoroethylene.

In some instances the cables may be secured to the frame by means situated beyond the outer perimeter of the frame.

Referring to FIGS. 5 to 7 there is shown a nuclear fuel element tube bundle comprising fuel elements 40, end plates 42 and 44 having coolant passages 46 to 50 therethrough and each secured to the fuel elements 40 at one end. Three frames in the form of outer retaining rings 52, 54 and 56 are provided disposed at positions spaced longitudinally along the tube bundle. The outer retaining rings 52, 54 and 56 have recesses 58 to receive curved portions of each outermost nuclear fuel element 40 to hold them against lateral displacement relative to the frame. Wire cables 60 have sufficient flexibility to pass over and under one another to form a lattice structure with the fuel elements 40 in the lattice interstices.

In the embodiment shown in FIGS. 8 and 9 the wire cables 60 are in contact with sleeves 62 which are brazed or welded to the fuel sheaths of fuel elements 40 to prevent wear of the fuel sheaths by the wire cables 60.

In FIG. the wire cables 60 are arranged in a lattice similar to that shown in FIG. 7, but each extend along one plane and do not pass over and under one another. This embodiment is neater and geometrically more stable than the embodiment shown in FIGS. 5 to 7, but it is then necessary as shown for the cables 60 of each lattice to be arranged in four cable levels instead of the two cable levels shown in FIG. 5. This embodiment may also provide less obstruction to the flow of coolant through t e lattice.

In some embodiments of the resent invention it might be advantageous to use two different sizes of wire cables. This would probably allow greater flexibility in the lattice design.

Depending on the design of the fuel bundle, one or more outer retaining rings 52, 54 or 56 may be fitted to the fuel bundle.

In some embodiments of the present invention it may be necessary or desirable to have more or less than four cable levels shown in FIG. 10.

In other embodiments of the present invention all of the tubes including the outermost are in a lattice interstice, this may be accomplished by, for example, using a rectangular frame.

In all of the embodiments of the resent invention the geometrical interference, caused y each cable being deflected round a tube, constrains the cable to bend and any flexural rigidity of the cables contributes greatly to the positive holding characteristic of the tubes by the cables.

I claim:

1. A tube bundle assembly, comprising a bundle of laterally spaced tubes, a frame around the outermost tubes, a lattice of wire cables with their ends held against lateral displacement by the frame and at least all but the outermost tubes each in a lattice interstice, and each wire cable deflected round a portion of each tube adjacent thereto to space the tubes in triangular arrays in an endwise direction.

2. An assembly according to claim 1, wherein cables tensioning means, secures each cable to the frame.

3. An assembly according to claim 1, which includes further wire cables extending along paths between the tubes on either side of the positions at which the lattice wire cables cross one another, the further wire cables have their ends held against lateral displacement b the frame and are deflected round the tubes to space them.

4. An assembly according to claim 1, wherein the outermost tubes are held in position by being located in recesses in the frame.

5. An assembly according to claim 1, wherein the wire cables are circular in cross-section.

6. An assembly according to claim 1, wherein the frame and wire cables are at one end of the tubes, a similar frame and lattice of wire cables is around the other end of the tubes, a casing is rovided around the tubes, and the frames locate the tu e bundle in the casmg.

7. An assembly according to claim 1, wherein the bundle of laterally spaced tubes is a nuclear fuel element tube bundle, the frame is disposed at an intermediate osition along the length of the bundle, and the assem ly further comprises two end plates having coolant passages and attached one at each end of the fuel bundle.

8. An assembly according to claim 7, wherein the frame and lattice of wire cables is one of a plurality of similar frames and lattices of wire cables each spaced from one another along an intermediate portion of the length of the nuclear fuel element bundle.

9. An assembly according to claim 7, wherein sleeves are attached to sheaths of the fuel elements for contact with the wire cables to prevent wear of the sheaths by the wire cables.

NITED STATES PATENT mm CERTEFICAT 0F 3,837,397 Dated September 24, 1974 Patent No.

',Inventor(s) Michel J. Pettigrew I I to It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

after [75] add:-

"[73] Assignee: The United States of America as represented by the United States Atomic Energy Commission, Washington,

Signedand 's ealed this 28th day of January 1975.

(SEAL Attest:

MCCOY M. GIBSON JR.- C. MARSHALL DANN Attesting Officer; l Commissioner of Patents FORM po'wso v, USCOMM-DC 60376-P69 v U.5. GOVER NMENT PRINTING OFFICE I969 0-356-334, 

1. A tube bundle assembly, comprising a bundle of laterally spaced tubes, a frame around the outermost Tubes, a lattice of wire cables with their ends held against lateral displacement by the frame and at least all but the outermost tubes each in a lattice interstice, and each wire cable deflected round a portion of each tube adjacent thereto to space the tubes in triangular arrays in an endwise direction.
 2. An assembly according to claim 1, wherein cables tensioning means, secures each cable to the frame.
 3. An assembly according to claim 1, which includes further wire cables extending along paths between the tubes on either side of the positions at which the lattice wire cables cross one another, the further wire cables have their ends held against lateral displacement by the frame and are deflected round the tubes to space them.
 4. An assembly according to claim 1, wherein the outermost tubes are held in position by being located in recesses in the frame.
 5. An assembly according to claim 1, wherein the wire cables are circular in cross-section.
 6. An assembly according to claim 1, wherein the frame and wire cables are at one end of the tubes, a similar frame and lattice of wire cables is around the other end of the tubes, a casing is provided around the tubes, and the frames locate the tube bundle in the casing.
 7. An assembly according to claim 1, wherein the bundle of laterally spaced tubes is a nuclear fuel element tube bundle, the frame is disposed at an intermediate position along the length of the bundle, and the assembly further comprises two end plates having coolant passages and attached one at each end of the fuel bundle.
 8. An assembly according to claim 7, wherein the frame and lattice of wire cables is one of a plurality of similar frames and lattices of wire cables each spaced from one another along an intermediate portion of the length of the nuclear fuel element bundle.
 9. An assembly according to claim 7, wherein sleeves are attached to sheaths of the fuel elements for contact with the wire cables to prevent wear of the sheaths by the wire cables. 